Various materials have been used as agricultural and horticultural mulch to enhance plant growth and improve soil, e.g. by conserving water, elevating soil temperature, controlling weeds, and adding organic mater to soils. Such materials have included straw, composted matter, manure, shredded bark and wood, fabric and plastic film. A decision to use mulch is usually based on the ability to achieve improvements over non-mulching agriculture practices which may require intense cultivation to control weeds and conserve water. Among the common mulch materials, plastic film is preferred for use with many cash crops, e.g. vegetables and ornamentals, due to its low cost and effectiveness in weed control and elevating soil temperature. Among the disadvantages of plastic film are poor distribution of irrigated water and the need to strip the film from fields after the growing season. Moreover, plastic film does not improve soil as organic mulch materials can do when incorporated into the soil. A soil with preferred tilth may comprise equal volumes of air, aggregate, organic matter and water. An advantage of a biodegradable mulch mat is that it can contribute to a preferred level of tilth when incorporated into the soil.
Likewise, in horticulture a variety of materials have been used to improve the aesthetic appearance of landscaping, suppress weeds and conserve moisture in soil around ornamental plants. Such materials include peat moss, chopped bark, shredded wood, compost, gravel and the like. Each of the materials has one or more deficiencies, e.g. with regard to weed suppression, moisture retention, biodegradation and appearance.
Jamison discloses in U.S. Pat. No. 3,812,615 a foamed material comprising fiber and an epoxy-crosslinked, acrylic polymeric binder intended as an agricultural mulch. The epoxy crosslinker renders the binder relatively non-biodegradable. And, as disclosed in comparative Example 13, such foamed material is not effective in suppressing weeds.